1. Field of the Invention
The present invention relates to a lens barrel having an iris diaphragm that adjusts an amount of incident light and an image pickup apparatus such a film camera or a digital camera having the lens barrel built-in.
2. Description of the Related Art
A digital camera in which a lens barrel having an iris diaphragm is mounted increases in thickness with respect to its optical axis direction by the thickness of the iris diaphragm when the lens barrel is stored.
Thus, there is conventionally discussed a technique of reducing the thickness of a camera in its optical axis direction by arranging the diaphragm on the object side of a lens unit and inserting the lens unit into an opening of shutter blades or diaphragm blades when the lens barrel is stored (see Japanese Laid-Open Patent Publication (Kokai) No. 2004-347615, for example).
In the technique of Japanese Laid-Open Patent Publication (Kokai) No. 2004-347615, a lens unit and a lens holding frame that holds the lens unit are inserted into the opening of the diaphragm blades in the optical axis direction, which requires the whole diaphragm blades to be retracted outwardly in a radial direction of the lens unit and the lens holding frame when the lens barrel is stored.
This increases the area of the diaphragm blades to increase an outer diameter of the whole diaphragm, which increases the diameter of the lens barrel. Consequently, the thickness of the camera reduces in its optical axis direction, which, however, increases the height and width dimensions, thereby leading to an increasing size of a camera.